This will be all too short, but I can’t let the publication of a new giant sauropod pass unremarked. Yesterday Bernardo González Riga and colleagues published a nice, detailed paper describing Notocolossus gonzalezparejasi, “Dr. Jorge González Parejas’s southern giant”, a new titanosaur from the Late Cretaceous of Mendoza Province, Argentina (González Riga et al. 2016). The paper is open access and freely available to the world.

As you can see from the skeletal recon, there’s not a ton of material known from Notocolossus, but among giant sauropods it’s actually not bad, being better represented than Argentinosaurus, Puertasaurus, Argyrosaurus, and Paralititan. In particular, one hindfoot is complete and articulated, and a good chunk of the paper and supplementary info are devoted to describing how weird it is.

But let’s not kid ourselves – you’re not here for feet, unless it’s to ask how many feet long this monster was. So how big was Notocolossus, really?

Well, it wasn’t the world’s largest sauropod. And to their credit, no-one on the team that described it has made any such superlative claims for the animal. Instead they describe it as, “one of the largest terrestrial vertebrates ever discovered”, and that’s perfectly accurate.

Any discussions of the size of Notocolossus will be driven by one of two elements: the humerus and the anterior dorsal vertebra. The humerus is 176 cm long, which is shorter than those of Giraffatitan (213 cm), Brachiosaurus(204 cm), and Turiasaurus (179 cm), but longer than those of Paralititan (169 cm), Dreadnoughtus(160 cm), and Futalognkosaurus (156 cm). Of course we don’t have a humerus for Argentinosaurus or Puertasaurus, but based on the 250-cm femur of Argentinosaurus, the humerus was probably somewhere around 200 cm. Hold that thought.

Top row: my attempt at a symmetrical Notocolossus dorsal, made by mirroring the left half of the fossil from the next row down. Second row: photos of the Notocolossus dorsal with missing bits outlined, from Gonzalez Riga et al (2016: fig. 2). Scale bar is 20 cm (in original). Third row: the only known dorsal vertebra of Puertasaurus, scaled to about the same size as the Notocolossus vertebra, from Novas et al. (2005: fig. 2).

The anterior dorsal tells a similar story, and this is where I have to give González Riga et al. some props for publishing such detailed sets of measurements in the their supplementary information. They Measured Their Damned Dinosaur. The dorsal has a preserved height of 75 cm – it’s missing the tip of the neural spine and would have been a few cm taller in life – and by measuring the one complete transverse process and doubling it, the authors estimate that when complete it would have been 150 cm wide. That is 59 inches, almost 5 feet. The only wider vertebra I know of is the anterior dorsal of Puertasaurus, at a staggering 168 cm wide (Novas et al. 2005). The Puertasaurus dorsal is also quite a bit taller dorsoventrally, at 106 cm, and it has a considerably larger centrum: 43 x 60 cm, compared to 34 x 43.5 cm for Notocolossus (anterior centrum diameters, height x width).

Centrum size is an interesting parameter. Because centra are so rarely circular, arguably the best way to compare across taxa would be to measure the max area (or, since centrum ends are also rarely flat, the max cross-sectional area). It’s late and this post is already too long, so I’m not going to do that now. But I have been keeping an informal list of the largest centrum diameters among sauropods – and, therefore, among all Terran life – and here they are (please let me know if I missed anyone):

(Fine print: I’m only logging each taxon once, by its largest vertebra, and I’m not counting the dorsoventrally squashed Giraffatitan cervicals which get up to 47 cm wide, and the “uncatalogued” Supersaurus dorsal is one I saw back in 2005 – it almost certainly has been catalogued in the interim.) Two things impress me about this list: first, it’s not all ‘exotic’ weirdos – look at the giant Oklahoma Apatosaurus hanging out halfway down the list. Second, Argentinosaurus and Puertasaurus pretty much destroy everyone else by a wide margin. Notocolossus doesn’t seem so impressive in this list, but it’s worth remembering that the “max” centrum diameter here is from one vertebra, which was likely not the largest in the series – then again, the same is true for Puertasaurus, Alamosaurus, and many others.

As for the estimated mass of Notocolossus, González Riga et al. (2016) did their due diligence. The sections on mass estimation in the main text and supplementary information are very well done – lucid, modest, and fair. Rather than try to summarize the good bit, I’ll just quote it. Here you go, from page 7 of the main text:

The [humeral] diaphysis is elliptical in cross-section, with its long axis oriented mediolaterally, and measures 770 mm in minimum circumference. Based on that figure, the consistent relationship between humeral and femoral shaft circumference in associated titanosaurian skeletons that preserve both of these dimensions permits an estimate of the circumference of the missing femur of UNCUYO-LD 301 at 936 mm (see Supplementary Information). (Note, however, that the dataset that is the source of this estimate does not include many gigantic titanosaurs, such as Argentinosaurus[5], Paralititan[16], and Puertasaurus[11], since no specimens that preserve an associated humerus and femur are known for these taxa.) In turn, using a scaling equation proposed by Campione and Evans[20], the combined circumferences of the Notocolossus stylopodial elements generate a mean estimated body mass of ~60.4 metric tons, which exceeds the ~59.3 and ~38.1 metric ton masses estimated for the giant titanosaurs Dreadnoughtus and Futalognkosaurus, respectively, using the same equation (see Supplementary Information). It is important to note, however, that subtracting the mean percent prediction error of this equation (25.6% of calculated mass[20]) yields a substantially lower estimate of ~44.9 metric tons for UNCUYO-LD 301. Furthermore, Bates et al.[21] recently used a volumetric method to propose a revised maximum mass of ~38.2 metric tons for Dreadnoughtus, which suggests that the Campione and Evans[20] equation may substantially overestimate the masses of large sauropods, particularly giant titanosaurs. Unfortunately, however, the incompleteness of the Notocolossus specimens prohibits the construction of a well-supported volumetric model of this taxon, and therefore precludes the application of the Bates et al.[21] method. The discrepancies in mass estimation produced by the Campione and Evans[20] and Bates et al.[21] methods indicate a need to compare the predictions of these methods across a broad range of terrestrial tetrapod taxa[21]. Nevertheless, even if the body mass of the Notocolossus holotype was closer to 40 than 60 metric tons, this, coupled with the linear dimensions of its skeletal elements, would still suggest that it represents one of the largest land animals yet discovered.

So, nice work all around. As always, I hope we get more of this critter someday, but until then, González Riga et al. (2016) have done a bang-up job describing the specimens they have. Both the paper and the supplementary information will reward a thorough read-through, and they’re free, so go have fun.

Actually, I rather like the Noto– prefix (meaning Southern) as in Notoceratops and indeed Giganotosaurus. It also crops up, in a different form, in the plant genus Nothofagus, the so-called “southern beeches”.

Am I the only one wondering why the skeletal has 13 cervicals?
None of its sister taxa, or other relatives have 13 cervicals. The only titanosaur that has a completely preserved cervical column is Futalognkosaurus and it has only 10-11 cervicals. Dreadnoughtus doesn’t have a compete enough cervical column to bracket from. Its other closest relative Tapuiasaurus doesn’t have enough cervicals to support the idea of Lithostrotians having ~13 cervicals.
Not that I’m calling Gonzales et al. liars, nor am I criticizing their expertise. I’m just wondering where they got that number from.

Luigi, good question. The skeletal reconstruction has 14 cervical vertebrae, although at first glance it looks like 13 since the atlas (cervical 1) is small. We based this number off of Futalognkosaurus, which as you note has a complete neck. However, the neck of Futa has 14 cervicals, not 10-11. See papers by Calvo et al. (2007a, 2007b). Here are links to freely download these papers:

About centra (anserw about Ruyangosaurus dorsals from China – 2013-12-27

Dear Krzysztof Stuchlik,

Thank you for your enquiry.

We are displaying the reconstruction of Daxiatitan binglingi, but not Huanghetitan ruyangensis. The total body lengths of Daxiatitan and Huanghetitan are estimated to be 30 and 18 metres respectively.

About 270 pieces of fossils, including sacral vertebrae, dorsal vertebrae, ribs, femur and tibia of Ruyangosaurus giganteus were unearthed since 2006. One of the vertebrae is huge and measures up to 68 centimetres in diameter. This is the thickest vertebral ever discovered in the world so far. We are displaying this vertebra and another 13 real fossils of vertebrae and a replica of femur of Ruyangosaurus.

Thanks, everyone, for the comments. Matt and Bernardo, I’m glad you liked the post. I liked your paper – congratulations!

Shahen, thanks for the information. Do you know if any measurements or scaled photos of the 68-cm vertebra have been published? I haven’t seen any, and I’m a bit skeptical about that measurement for the following reasons:

(1) A centrum 68 cm in diameter would be more than 10% larger than the centra of Puertasaurus and Argentinosaurus. But the other elements of Ruyangosaurus measured by Lu et al. (2009) suggest an animal somewhat smaller than either. For example, Lu et al. estimated that the complete femur was 200 cm, compared to 250 cm for Argentinosaurus.

(2) That measurement is not mentioned by Lu et al. (2009), which is odd, since – as SO Chu Wing notes – it would be the largest vertebra by diameter of any animal, ever. Unless this is from another find, or from material prepared after the publication of Lu et al. (2009)?

(3) The wording is strange – “up to” 68 cm in diameter – which makes me think that possibly the measurement was not taken across either of the articular surfaces, or that it is an estimate from incomplete material, or that it was taken from a distorted vertebra whose dimensions were exaggerated by crushing. This does happen – Curtice et al. (1996) reported that the anterior centrum height for BYU 9044, a dorsal of Supersaurus, is 50 cm as preserved, but the vertebra is clearly distorted and they estimated that the actual diameter in life was more like 36 cm.

On the other hand, presumably SO Chu Wing is reporting accurately, It’s just hard to square the reported dimension with everything else we know about Ruyangosaurus. I’d like to get in touch with Wing and see if we can get more information and possible a photo. If you have an email address you’d be willing to share, please drop me a note at mathew.wedel@gmail.com.

From what I can gather from the website, the Hong Kong Science Museum seems to be a purely educational institution, without collections or a collections-oriented curatorial staff. The current staff chart (here) does not list a SO Chu Wing, so I’m guessing that person either is no longer employed at the museum, or is actually a curator at another museum commenting on the traveling exhibition. I intend no disrespect to SO Chu Wing, it just seems like their connection to the actual fossils might be a bit tenuous (and as always, please do set me straight if I’m mistaken).

The more I think about it, the more I suspect that the “up to 68 cm” refers to the possible dimensions of an incomplete vertebra – like the big cervical illustrated by Lu et al. (2009), the cotyle of which is only about half complete. That would essentially explain everything. FWIW, Lu et al. (2009) give a centrum width of 51 cm for that vertebra, and although they do not provide measurements for the complete dorsal vertebra, from the scaled photo it also seems to have a max diameter of 51 cm.

In any case, given that the only report of the 68-cm diameter vertebra comes from an email from a curator linked to a traveling educational exhibit, and given the odd wording, I am inclined to discount it. It’s almost impossible to rule out a typo, misunderstanding, or exaggeration (possibly well upstream of SO Chu Wing) as the source of the reported dimension. And so far, there is no other evidence to support it, and in fact what other evidence is available is inconsistent (as explained in my last comment).

I’d love to be wrong about this, so if anyone has any more information, please let me know!

First, good catch on Dreadnoughtus – I had missed that completely. According to Lacovara et al. (2014) Supplementary Table 1, ?D4 has a cotyle 44cm tall and 46cm wide, ?D5 has a condyle 47cm tall, ?D7 has a cotyle 43cm wide, and ?D8 has a cotyle 47cm wide. Some of those might be exaggerated a bit by distortion – the ?D8 cotyle is only 24cm tall – but the ?D4 cotyle is approximately circular so can’t be explained by squishing. I’ll update the post shortly.

As for Ruyangosaurus, the claim of 14 dorsal vertebrae is an immediate red flag. That would be unprecedented for any neosauropod. And from the photo, it looks like there’s some “plastersaurus” going on in the middle of the series, like one fragmentary vertebra was built out into at least one and possibly two additional ones. That could be how they got 14 exhibited dorsals out of a probable 12.

Anyway, the claimed count of 14 does not inspire my confidence that the person has much familiarity with sauropod anatomy – and so my confidence in the 68cm vertebra diameter is correspondingly decreased.

The femur was 230 cm (not 200 cm like first in paper)

Is that based on a new, complete femur, or a reconstruction, or an estimate?

From what I know about the one David Attenborough was talking about (= the one just mounted at the AMNH), Notocolossus is different. Firstly, Notocolossus was found in Mendoza province and not Chubut where the ‘AMNH’ one was discovered. Secondly, the ‘AMNH’ titanosaur is known from much more material. We don’t have the femur of Notocolossus, but we do have the femur of the ‘AMNH’ titanosaur. From what I’ve heard, a description is in the works. They seem to be taking their time, which is good.

Thanks for the correction, Matt! When I mentioned the numbers 10-11, I was mistakenly remembering the number DORSALS for Futalognkosaurus instead of the cervicals. The paper reported it having 10-11 dorsals, and 14 cervicals. My mistake.

We should really ping Scott Hartman for his thoughts on that – and I’ll do that shortly – but from looking at mounts and skeletal recons of big (and tall) critters like Giraffatitan and Argentinosaurus, my guess is 6-7 meters. Anyone have anything more precise? And if so, how, given the uncertainties with reconstructing the incomplete big ones?

[…] At SVPOW, Matt Wedel covers the new giant titanosaur Notocolossus. He covers some pretty interesting stuff about the morphology of the giant’s bones, including the fact that the known vertebrae of Notocolossus are remarkably similar to those known of Puertasaurus. You can find this post here. […]

Hi Liviu (and thanks for the ping, Matt). I just measured and I’m getting 7.15 meters right over the shoulders, which are usually the highest point on my reconstructions. Of course exactly how tall the back would have been depends on a series of interpretations about limb posture and pectoral girdle placement, but >7m seems like a good bet.

Here’s a thing. An average giraffe is about 5 m tall, and the tallest ever measured was about 6 m tall. That means that these titanosaur individuals — and remember there is no reason to think they are especially big representatives — are significantly taller at the shoulder than the top of the head of the word-record giraffe.

While we’re on the subject of how titanosaurs are better than giraffes, even the record largest giraffe individuals are still less than 1/50 the mass of your average lithostrotian.

Heck, Basu, Falkingham, and Hutchinson (2016) volumetrically estimated Sivatherium giganteum ,both the largest ruminant and the largest giraffe in history, at just 800kg-1,200 kg.Diplodocus alone is around 10 times more massive than that, and Diplodocus is considered slender and fairly average-sized for a neosauropod.

Speaking of intraspecific variability… how accurate a metric for ‘size comparisons’ do you think the centra (or, indeed, most bone) sizes really are? André the Giant and Peter Dinklage were / are both adult humans, but certainly have vastly different frames. I know it’s probably the best that we may be able to get, but I think it’s important to keep in mind.

Is this ever discussed in papers attempting to measure sauropods? Left the world of dead things for the world of live things, so have been out of the ‘literature loop.’

Speaking of intraspecific variability… how accurate a metric for ‘size comparisons’ do you think the centra (or, indeed, most bone) sizes really are?

Short answer: probably horrible. I collect them mainly for trivia, and because I’m interested in superlatives.

Long answer: centrum diameter is probably worse than most other single-bone measures, because of the complicating effect of pneumaticity. Let’s say a big, four-square quadruped of mass Y and athleticism Z needs a mid-dorsal centrum cross-sectional area of X. If that quadruped is Jobaria, which has apneumatic dorsal centra past about D3 or D4, the centrum may actually have a cross-sectional area of X. But if the dorsal centra are pneumatized, the same cross-sectional area of bone can be distributed more widely for a negligible increase in mass. If the air space proportion (ASP) is 0.5, meaning the vertebra is 50% air (e.g., Camarasaurus, X bone can be spread over an area of 2X. If the ASP is 75% (Giraffatitan), 4X, and if 87.5% (Sauroposeidon, “Angloposeidon”), 8X. That’s simplistically assuming that the cross-sectional area of bone tissue has to remain the same – it is more likely that the more pneumatic taxa could get away with less bone by deploying it more advantageously. Still, it illustrates the problem of comparing centra across taxa of varying ASPs – which is pretty much all of them, among sauropods.

It would be VERY interesting to make a big table of humerus and femur cross-sectional areas, mid-dorsal cross-sectional area “as-is”, and mid-dorsal cross-sectional area “corrected” for ASP, and see if there are any correlations. I’m the obvious person to do that, but I’m already snowed under with other things I’m even more interested in doing, so I’m releasing that idea into the wild. Anyone who is interested should feel free to run with it.

Gunnar to the rescue! According to Lu, et. al. 2014, the centrum width of the dorsosacral of Ruyangosaurus is 68cm. This is by far the widest centrum I’ve come across for any dinosaur. As for the dorsals, Lu, et. al. found 13 at the site (excluding the two holotypic dorsals), but most of these appear to actually overlap rather than belonging to a single complete sequence of vertebrae.

The holotype femur as preserved is 120cm long, & was originally restored as 235cm. A second smaller, complete femur (167cm) was recovered from the site, but this femur looks far more euhelopodid than any sort of lognkosaur or other basal titanosaur femur, & it certainly doesn’t match the holotype femur very well (interestingly enough though, that of Patagotitan does, as do the posterior dorsals).